This is a study to compare the efficacy and tolerability of two laxatives for treatment of opioid-induced constipation in adult outpatients with cancer treated at the BC Cancer Agency Pain and Symptom Management/Palliative Care clinics. Each participating patient will be randomly assigned to one of two treatment groups.

Stepped bowel protocol with PEG for 3 weeks followed by senna for 3 weeks. Both active treatments accompanied by placebo of alternate (lactose powder).

Other Name: Lax-a-Day

Experimental: Senna then PEG

Stepped bowel protocol with Senna then PEG

Drug: Senna then PEG

Stepped bowel protocol with senna for 3 weeks followed by PEG for 3 weeks. Both active treatments accompanied by placebo of alternate (lactose powder).

Detailed Description:

One group will be started on a bowel protocol of escalating doses of sennosides, plus a dummy polyethylene glycol (lactose), and the other will receive dummy sennosides capsules (lactose)plus polyethylene glycol, with the same dosing protocol. After three weeks the patients will switch to the alternate active product and dummy preparation. The total duration for the study will be 6 weeks for each patient.

On opioid therapy with daily dose range no more than 30% of minimum daily consumption over previous 7 days.

Patients may be included if they have previously been taking laxatives but are still constipated (BPS -2 or less).

Exclusion Criteria:

Patient unable to take oral medication.

New treatment expected to affect bowel function during the study (6 weeks), e.g. opioid rotation, commencement of drug with laxative/constipating effect, such as misoprostol, ondansetron etc.

Allergy or previous intolerance to PEG or sennosides.

Lactose intolerant.

Contraindication to PEG or sennosides.

Known or suspected bowel obstruction or ileus.

Colostomy or ileostomy.

Inflammatory bowel disease.

Hospitalisation expected within the study period.

Patient unable to complete the study diary in English.

Contacts and Locations

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Please refer to this study by its ClinicalTrials.gov identifier: NCT01189409